public String largestGoodInteger(String num) {
    //Scanner sc = new Scanner(System.in);
    //String num=sc.next();
    char[] ar = num.toCharArray();
    ArrayList<String> l = new ArrayList<>();
    ArrayList<String> l2 = new ArrayList<>();
    String str="";
    int flag=0;
    for(int i=0;i<num.length()-2;i++){
        if(ar[i]==ar[i+1] && ar[i+1]==ar[i+2]){
            flag=1;
            str=Character.toString(ar[i])+Character.toString(ar[i+1])+Character.toString(ar[i+2]);
            l.add(str);
        }
    }
    String s="";
    if(flag==0){
        System.out.println("");
    }
    else {
        /*for (int i = 0; i < l.size(); i++) {
            System.out.println(l.get(i) + " ");
        }*/
        int temp = 0;
        for (int k = 0; k < l.size(); k++) {
            l2.add(l.get(k));
        }
        int max = Integer.MIN_VALUE;

        for (int j = 0; j < l.size(); j++) {
            if (Integer.parseInt(l.get(j)) > max) {
                max = Integer.parseInt(l.get(j));
                temp = j;
            }

        }
        //String s=Integer.toString(l2.get(temp));
        s = l2.get(temp);
        
    }
    return s;

}